Push–Pull Stabilization of Parent Monochlorosilylenes

Abstract

While reaction of carbene-stabilized disilicon L:Si═Si:L (L: = C{N(2,6-(i)Pr2C6H3)CH}2) (8) with HCl·NC5H5 results in carbene-stabilized Si2Cl2 (2) and substituted 1H-imidazole (9), combination of the corresponding Fe(CO)4-modified disilicon carbene complex L:Si═Si[Fe(CO)4]:L (6) with pyridine hydrochloride gives a species containing two push-pull-stabilized parent monochlorosilylenes that are bridged by an Fe(CO)3 unit (7). The nature of 7 was further elucidated by spectroscopic, crystallographic, and computational methods. Spectroscopic data suggest that 7 exists as two diastereoisomers.

NHCs in Main Group Chemistry

“…However, the synthesis of a stable complex of the related monochlorosilylene (HClSi:), which has been observed concomitantly with the former silylenes in the chemical vapor deposition of silicon from chlorosilanes and SiH 4 , still has to be achieved. Thus, to gain access to a stabilized HClSi: moiety, Robinson and co-workers treated complex 572 with pyridine hydrochloride py·HCl . Nevertheless, the reaction does not furnish a monochlorosilylene species, but a rather complicated mixture containing among others the NHC-stabilized bis­(silylene) 603 , dihydroaminal IDippH 2 , and free IDipp.…”

Facile Conversion of Bis-Silylene to Cyclic Silylene Isomers: Unexpected C–N and C–H Bond Cleavage

“…The H(1) atom bound to the four-coordinate Si(1) atom in 3 renders 4.61 ppm 1 H NMR resonance, which was located in the difference Fourier map. The SiH coupling constants ( 1 J Si–H = 195 Hz and 2 J Si–H = 20 Hz) shown in the proton-coupled 29 Si NMR spectrum of 3 (Figure ) compares well to those obtained from low-intensity 29 Si satellites in the 1 H NMR spectrum of 3 ( 1 J Si–H = 196 Hz and 2 J Si–H = 20 Hz) and the average 1 J Si–H value (195 Hz) observed in the 29 Si NMR spectrum of a “push–pull”-stabilized parent monochlorosilylene [:Si­(H)­Cl] ( 5 ) . The SiH IR stretching band (ν = 2109 cm –1 ) for 3 is between that (ν = 2103 cm –1 ) for 5 and that (ν = 2118 cm –1 ) for L 2 SiH 2 Cl 2 [L: = :C­{N­(2,6-Pr i 2 C 6 H 3 )­CH} 2 ] .…”

Base-stabilized formally zero-valent mono and diatomic molecular main-group compounds

“…Robinson and co-workers have also isolated a push-pull stabilized parent chloro-silylene (96) by reacting complex 95 with pyridine hydrochloride (HCl•NC 5 H 5 ) (Scheme 26). 121 The two silicon centres in complex 96 are chiral, and 29 Si{ 1 H} NMR spectrum showed two signals at δ = 44.02 and 45.32 ppm due to two diastereomers. The 29 Si NMR spectrum showed four signals with J Si-H = 192 Hz (average).…”

“…The reaction of pyridine hydrochloride with 90 yielded a complex mixture of products from which the authors could identify and characterize 97 and dihydroimidazole (Scheme 26). 121 It was anticipated to proceed through the formation of an NHC-stabilized parent chloro-silylene which subsequently decomposed due to the absence of an acceptor group.…”